1) Technical Field
The present invention generally relates to microelectronic circuits. More particularly, the present invention relates to a circuit configured to differentiate a xe2x80x9cvalidxe2x80x9d transmitted signal from noise signals transmitted over a transmission line.
2) Background of the Invention
When electronic signals are transmitted from one location to another along a line (e.g., a fiber optic cable or the like), electronic noise is often also transmitted with the signal along the line. In many cases, it is desirable to determine when a xe2x80x9cvalidxe2x80x9d electronic signal from a transmission source, rather than just electronic noise, is transmitted over the line. For example, circuits such as clock and data recovery require a valid data input to operate properly. It is often necessary to first determine if the data signal is being properly transmitted. Accordingly, a circuit that is able to detect whether a xe2x80x9cvalidxe2x80x9d signal is transmitted is desired.
A circuit for the detection of a valid signal on a line of the present invention includes an offset generator, a pair of data slicers, and an XOR gate. The circuit may also contain, for purposes of smoothing the response of the circuit, a low-pass filter and a Schmitt trigger.